A grass mower according to U.S. Pat. No. 8,690,190 includes a vehicle body frame extending between a left rear wheel and a right rear wheel, an engine mounted rearwardly of a driver's seat, a fuel tank disposed downwardly of the driver's seat, a left hydraulic stepless speed changing device for transmitting drive power to the left rear wheel, and a right hydraulic stepless speed changing device for transmitting drive power to the right rear wheel. For improvement of front-rear balance of the vehicle body, the engine needs to be disposed as forwardly as possible. As a result, the distance between the driver's seat and the engine is set small. In the periphery of the driver's seat, there are disposed various electric operating tools, sensors, display units, etc. Further, there are present in a mixed state, a cable harness combining multiple signal cables (lines) for transmitting electric signals from such operating tools and sensors to a controller and signal lines for sending electric signals from the controller to the operating devices or the displaying units as well as a hydraulic hose connecting between the hydraulic stepless speed changing device and the oil tank. If interference occurs between the cable harness and the hydraulic hose, trouble or difficulty will be encountered in assembly or maintenance.
Thus, there is a need to arrange a fuel tank, an engine, a hydraulic stepless speed changing device and an oil tank for the hydraulic stepless speed changing device with good balance downwardly or rearwardly of the driver's seat so as to effectively avoid entanglement between pipes of the hydraulic stepless speed changing device and the cable harness.